MK-677 Research Overview (also known as Ibutamoren, Ibutamoren Mesylate)
A non-peptide GH secretagogue (ghrelin mimetic) that activates the ghrelin receptor to stimulate GH and IGF-1 secretion. Distinguished by its oral bioavailability, eliminating the need for injection. Studied for lean mass preservation, recovery, sleep quality improvement, and GH-axis support.
What Is MK-677?
MK-677 (Ibutamoren) is a potent, orally active, non-peptide GH secretagogue — a ghrelin receptor (GHSR-1a) agonist that mimics ghrelin's ability to stimulate pituitary GH release. Developed by Merck, it was the first orally bioavailable GH secretagogue to enter clinical trials. Unlike all other GH secretagogues (which are peptides requiring injection), MK-677 survives oral administration intact and produces sustained elevations in both GH and IGF-1 over a 24-hour period from a single daily dose.
Mechanism and Pharmacokinetics
MK-677 activates GHSR-1a on pituitary somatotrophs with high affinity and selectivity. Its non-peptide structure allows oral bioavailability of approximately 60–70%, and its 4–6 hour half-life produces a sustained GH secretory response that maintains IGF-1 elevation throughout the day — a 24-hour profile that distinguishes it from injectable GH secretagogues whose effects are more pulsatile.
Clinical Research Findings
Clinical trials in healthy elderly adults demonstrated significant increases in GH and IGF-1 levels (to young adult ranges), improved body composition (increased lean mass, decreased fat mass), improved sleep quality (particularly slow-wave sleep), and normalized bone turnover markers. A 2-year trial showed sustained GH/IGF-1 elevation and lean mass preservation without significant adverse effects beyond mild fluid retention at higher doses.
Quick Reference
| Literature-Reported Dose Range | 25mg |
| Literature-Reported Frequency | 1x daily |
| Literature-Reported Cycle Length | 8-12 weeks |
| Literature-Reported Washout | 8-12 weeks minimum |
| Storage | Room temp, dry place |
| Timing | Bedtime, empty stomach |
Research Indications
Tissue Repair
Muscle Preservation
Reverses diet-induced catabolism with significant nitrogen retention supporting muscle preservation during caloric restriction.
Body Composition
Increases fat-free mass while improving metabolic rate through sustained growth hormone elevation.
Bone Health
Increases bone formation markers supporting skeletal health through growth hormone axis activation.
Anti-Aging
Growth Hormone Restoration
Restores youthful GH/IGF-1 levels in elderly subjects addressing age-related hormone decline.
Sleep Quality
Significantly improves sleep architecture and REM sleep, particularly beneficial in older adults.
Metabolic Benefits
Sustained IGF-1 elevation supports metabolic function and healthy aging processes.
Energy Metabolism
Energy Expenditure
Increases basal metabolic rate contributing to improved energy utilization and body composition.
Recovery Enhancement
Improves recovery through growth factor elevation and enhanced sleep quality.
Appetite Regulation
Ghrelin receptor activation affects appetite - beneficial for muscle building but may impact fat loss goals.
Research Protocols
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
| Research Application | Dose | Frequency | Route |
|---|
| Body composition/Anti-aging | 25mg | 1x daily | Oral (bedtime) |
| Sleep improvement | 25mg | 1x nightly | Oral (before bed) |
| Conservative start | 12.5mg | 1x daily | Oral (assess tolerance) |
Timing
Recommended administration window: bedtime, empty stomach. Typical onset: 2 weeks sleep, 12-16 weeks body composition.
Peptide Interactions
Complementary GH pathways - CJC-1295 provides pulsatile release while MK-677 maintains baseline elevation
Both stimulate GH release through different mechanisms, creating pharmaceutical-grade hormone levels
MK-677's sustained baseline elevation combines with GHRP-2's strategic pulsatile spikes
MK-677 enhances recovery and tissue repair effects through systemic growth factor elevation
Non-competing mechanisms - MK-677 provides systemic growth factors while BPC-157 offers localized healing
Redundant effects without proportional benefits - may increase side effect risk
MK-677 decreases insulin sensitivity - requires careful blood glucose monitoring with diabetes medications
Case report shows 85.7% testosterone suppression and 95.8% liver enzyme elevation when combined
Reported Research Timeline
01Week 1–2 (reported in cited studies): improved sleep quality, possible appetite increase
02Week 2–4 (reported in cited studies): enhanced recovery, initial body composition changes
03Week 4–8 (reported in cited studies): noticeable lean mass gains
04Week 8–12 (reported in cited studies): maximum benefits with sustained GH elevation
Side effects (reported in cited studies): appetite stimulation, water retention, possible lethargy
Safety Notes
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
FDA warns of significant cardiovascular risks including heart failure potential
Not Recommended in heart disease, diabetes, active cancer
Decreases insulin sensitivity - monitor blood glucose
Requires medical supervision and regular monitoring
Not FDA approved - investigational drug status only
Seek Medical Attention If:
Signs of heart failure or cardiovascular symptoms
Blood glucose elevation or diabetes symptoms
Liver enzyme elevation or unusual fatigue
Severe fluid retention or concerning side effects
Always consult healthcare provider immediately
Quality Indicators
Verified Marker
Authentic MK-677 / Ibutamoren Identity Confirmed by MS
MK-677 (Ibutamoren mesylate, MW 624.8 Da) should be confirmed by mass spectrometry. Counterfeiting with cheaper GHSs or random orals is documented in the RUO market. A CoA with MS identity confirmation is non-negotiable.
Verified Marker
Purity ≥98% HPLC with Third-Party CoA
Third-party lab testing (not just manufacturer-issued) significantly increases reliability. Look for HPLC purity ≥98% and a verifiable lab name on the CoA.
Verified Marker
Correct Formulation — Oral Capsule or Liquid
MK-677 is orally bioavailable. Legitimate products are capsules (typically 10–25 mg) or oral liquid solutions. Injectable claims are a major red flag — MK-677 is not used or validated as an injectable.
Quality Concern
SARMs Mixed Into the Same Product
Disreputable vendors mix MK-677 with SARMs (RAD-140, LGD-4033, Ostarine). These combinations are not disclosed on labels. Third-party testing revealing undisclosed compounds is the only reliable way to identify this.
Quality Concern
Underdosed Products
Independent testing has found a significant proportion of commercial MK-677 products to be underdosed by 20–50%. Verify by sourcing from vendors with current, verifiable third-party CoAs.
Research Citations
- Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects
Chapman, I.M., Bach, M.A., Van Cauter, E., et al., 1996, Journal of Clinical Endocrinology & Metabolism - MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism
Murphy, M.G., Plunket, L.M., Gertz, B.J., et al., 1998, Journal of Clinical Endocrinology & Metabolism - Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure
Svensson, J., Lönn, L., Jansson, J.O., et al., 1998, Journal of Clinical Endocrinology & Metabolism - Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man
Copinschi, G., Leproult, R., Van Onderbergen, A., et al., 1997, Neuroendocrinology - LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report
Cardaci, T.D., Machek, S.B., Wilburn, D.T., et al., 2022, Experimental Physiology - Structural basis of human ghrelin receptor signaling by ghrelin and the synthetic agonist ibutamoren
Liu, H., Kim, H.R., Deepak, R.N.V.K., et al., 2021, Nature Communications - Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial
Nass, R., Pezzoli, S.S., Oliveri, M.C., et al., 2008, Annals of Internal Medicine - MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study
Adunsky, A., Chandrasekaran, K., Wind, S., et al., 2011, Archives of Gerontology and Geriatrics - A Study of the Metabolism of Ibutamoren (MK-677), a Growth Hormone Secretagogue, in Human Urine by Ultra-High-Performance Liquid Chromatography–High-Resolution Mass Spectrometry
Dmitrieva, E.V., Anikina, L.V., Ostroukhova, T.V., et al., 2024, Journal of Analytical Chemistry - Effect of the Orally Active Growth Hormone Secretagogue MK-677 on Somatic Growth in Rats
Lee, J., Park, S., Lim, A., et al., 2018, Yonsei Medical Journal - MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism
Murphy MG, Plunkett LM, Gertz BJ, 1998, J Clin Endocrinol Metab - Oral administration of growth hormone (GH) releasing peptide-mimetic MK-677 stimulates the GH/insulin-like growth factor-I axis in selected GH-deficient adults
Chapman IM, Pescovitz OH, Murphy G, 1997, J Clin Endocrinol Metab - Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adults. The MK-677 Study Group
Murphy MG, Bach MA, Plotkin D, 1999, J Bone Miner Res - Effect of the Orally Active Growth Hormone Secretagogue MK-677 on Somatic Growth in Rats
Lee J, Kwon A, Chae HW, 2018, Yonsei Med J - Effect of alendronate and MK-677 (a growth hormone secretagogue), individually and in combination, on markers of bone turnover and bone mineral density in postmenopausal osteoporotic women
Murphy MG, Weiss S, McClung M, 2001, J Clin Endocrinol Metab
Research Focus
Growth hormone secretion, IGF-1 elevation, Muscle mass, Sleep quality, Anti-aging, Oral GHS
Verified Vendors Carrying MK-677
Frequently Asked Questions
What should researchers watch for with MK-677?
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
What should researchers expect over time with MK-677?
Week 1–2 (reported in cited studies): improved sleep quality, possible appetite increase
How is MK-677 typically administered in research?
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
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